1. Field of the Invention
This invention relates to an image forming medium which functions by utilizing the chemical or physical change of a monomolecular film of a diacetylene (or polydiacetylene) derivative compound or its built-up film, and to an image forming device by utilizing the same.
2. Related Background Art
In the prior art, various recording media have been known as the recording medium by use of an organic compound as the recording layer.
For example, Japanese Laid-open Pat. Publication No. 125246/1983 discloses an optical recording medium comprising a recording layer composed of a thin film of an organic compound.
This recording medium uses an organic dye for the recording layer, and record reproducing is effected with a laser beam.
The medium disclosed in Japanese Laid-open Pat. Publication No. 125246/1983 uses a thin film of a cyanine dye represented by the formula shown below as the recording layer: ##STR1## A solution of the cyanine dye represented by the formula (1) is applied by use of a rotary coater on a plastic substrate having a thickness of 1000 .ANG. or less, for example, about 300 .ANG., to form a thin film on the plastic substrate. If the molecules are distributed and oriented randomly within the film, light will be scattered in the film on light irradiation, and the degree of reaction occurring per every light irradiation will differ microscopically. Accordingly, as the recording medium, it is desirable that the molecular distribution and orientation within the film be uniform, and also the film is desirably to be as thin as possible for obtaining a higher density of recording. However, according to the coating method, the lower limit of the film thickness is about 300 .ANG., and it is hardly possible to solve the problem of random molecular distribution and orientation within the film.
In the prior art, LED.CRT liquid crystal device (hereinafter called LCD), electrochromic device (hereinafter called ECD), and electroluminescence device (hereinafter called ELD), etc. have been known as the displaying device.
Among them, LCD, ECD and ELD may be mentioned as the miniature and high-density devices. However, these devices involve a number of disadvantages as shown below.
(1) Film is thick and layer constitution is complicated.
(2) Electrode wiring is complicated.
(3) Not suited for ultra-high density and large area.
Further, LCD involves the problems:
(4) Direction of observation is limited.
(5) Response speed is slow.
ECD involves the problems:
(6) Use of an electrolyte necessitates assembly of a cell.
(7) Redox reaction in an electrolyte is susceptible to reactions with impurities.
(8) Safety is insufficient.
ELD has the problem:
(9) Luminance is low.